lengdeakse

Lengdeakse, or longitudinal axis, is an imaginary line that runs along the length of an object, typically from front to back (for example, nose to tail in a vehicle or fuselage). It serves as a reference axis for describing rotational motion and orientation in three-dimensional space. The term comes from the Norwegian words lengde (length) and akse (axis).

In practical use, lengdeakse is most commonly discussed in contexts such as aviation, maritime transport, robotics and biomechanics. In an aircraft, the lengdeakse runs along the fuselage from nose to tail, and rotation about this axis is called roll. The same concept applies to ships and other vehicles, where rolling describes tilting side to side around this lengthwise axis. In robotics and engineering, the axis provides a frame of reference for controlling orientation and movements around the length of a structure or device.

Lengdeakse is one of the three principal axes used in a standard three-axis body reference. The other two are tverakse (lateral or transverse axis), around which pitch occurs, and vertikalakse (vertical axis), around which yaw occurs. Together they describe the orientation and rotational degrees of freedom of a body in space. In Norwegian technical texts, lengdeakse is commonly translated as longitudinal axis and sometimes referred to as the X-axis in a chosen coordinate system.